Question

I’m writing a C++ Software Image processing tool.The tool works fine, but suddenly it stops and it never sends any exception or any crash or nothing that can let me which line or which area that does that crash.

How can I determine that faulty code in that situation?

Answer 1

There’s a few things you can do:

First of all though, it sounds more like an infinite loop, deadlock, or like you’re using all of your system resources and it’s just slowing down and taking a very (possibly infinite) long time. If that’s the case, you’ll have to find it with debugging.

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Things that you can try – not necessarily in this order:

1. Look for shared variables you’re using.  Is there a chance that you
   have a deadlock with threads and mutexes?  Think about it and try to
   fix it.

2. Check for use of uninitialized variables/pointers.  Sometimes
   (rarely) you can get very strange behavior when you invoke undefined
   behavior – I’m not a windows C++ dev (I work on Linux), but it
   wouldn’t be the first time I saw a lockup from a segmentation fault.

3. Add error output (std::cerr/stderror) to your processing logic so
   you can see how far in it crashes. After that, set a condition to
   catch it around that point so you can watch it happen in the
   debugger and see the state of your variables and what might be
   wrong.

4. Do a stack trace so you can see what calls have been hit most
   recently. This will at least let you know the last function chain
   that executed.